Top level deeplink handling (#1660)

* Handle link opening on the top most levels and prepare for percolating them throughout the app
* Add support for a custom app scheme
* Add specific AppRoute parsers.
* Integrate custom scheme in the AppRouteURLParser
* Switch to `element://call` and cleanup route parsing

ElementX/Sources/Application/AppCoordinatorProtocol.swift

@@ -18,5 +18,5 @@ import Foundation
 
 protocol AppCoordinatorProtocol: CoordinatorProtocol {
     var notificationManager: NotificationManagerProtocol { get }
-    func handleUniversalLink(_ url: URL)
+    @discardableResult func handleDeepLink(_ url: URL) -> Bool
 }